scholarly journals Numerical Studies and Analyses on the Acidizing Process in Vug Carbonate Rocks

2021 ◽  
Vol 9 ◽  
Author(s):  
Cunqi Jia ◽  
Kamy Sepehrnoori ◽  
Haiyang Zhang ◽  
Jun Yao

A vug porosity system, in addition to a matrix, is also the target rocks for the acidizing. In this work, the acidizing process in two typical core-scale separate-vug porosity systems is studied in detail. Numerous cases are conducted to discuss a parametric study on the acidizing process and hydraulic behavior. Results indicate that the presence of vug reduces the pore volume of acid solution consumed to achieve a breakthrough, which is consistent with experimental observations. Increasing the vug diameter and porosity decreases pore volume to breakthrough both for a vugular carbonate rock and isolated vug carbonate rock. In comparison, the acid mass does not change a lot. Typical dissolution patterns can also be observed in the acidizing process when a vug exists. Compared to matrix dissolution patterns, the presence of vug induces wormhole to pass through the vug region.

2015 ◽  
Vol 1092-1093 ◽  
pp. 1375-1378
Author(s):  
Qian Zhang ◽  
Wen Hui Huang ◽  
Ya Mei Zhang

Based on a large number of carbon and oxygen stable isotope data, researched environment characteristics of Ordovician carbonate rocks in Yubei area, Tarim Basin. According to carbon, oxygen stable isotopes (&13C, &18O) data, combining the diagenetic environment characteristics studied all kinds of geochemical characteristics of rocks in Yubei area. The research results show that: Paleosalinity feature of Ordovician carbonate rocks in this area reflected the carbonate rocks is formed in the stability of the marine environment and basically kept the composition of carbon and oxygen isotopic of the original environment. the paleo temperature characteristics indicate that the diagenetic burial depth was increased first and then decreased, the sea level characteristics indicate that the sedimentary strata by Yingshan period to Lianglitage period corresponds with a rise in sea level.


Author(s):  
Sumita Pennathur ◽  
Juan G. Santiago

We investigate electrokinetic transport in nanometer-scale fluidic channels. Our study includes numerical studies of nanofluidic transport of both charged and uncharged analytes in conditions of finite Debye layer thickness and high zeta potentials. The models are based on continuum mass transport and field theory. We also perform an experimental parametric study using etched nanoscale channels. Experimental results agree with model predictions and show that bulk electrokinetic transport in nanoscale channels depends strongly on the shape and size of the EDL and on the effects of transverse electrophoretic migration.


2013 ◽  
Vol 734-737 ◽  
pp. 207-210
Author(s):  
Hui Jian Wen ◽  
Qi Wang ◽  
Dong Yun Geng

To identify and segment automatically the apertures by using of differences between aperture area changes of the grayscale or chroma of carbonate rock and the surrounding rocks in imaging logging data. Contour extraction and contour tracing can extract the aperture boundary effectively, and calculate the aperture parameter which is unable to get quantitatively in common logging. Dealing with actual data, this method is confirmed to have a high precision.


2019 ◽  
Vol 11 (1) ◽  
pp. 1151-1167
Author(s):  
Waheed Ali Abro ◽  
Abdul Majeed Shar ◽  
Kun Sang Lee ◽  
Asad Ali Narejo

Abstract Carbonate rocks are believed to be proven hydrocarbon reservoirs and are found in various basins of Pakistan including Lower Indus Basin. The carbonate rock intervals of the Jakkher Group from Paleocene to Oligocene age are distributed in south-western part of Lower Indus Basin of Pakistan. However, there are limited published petrophysical data sets on these carbonate rocks and are essential for field development and risk reduction. To fill this knowledge gap, this study is mainly established to collect the comprehensive high quality data sets on petrophysical properties of carbonate rocks along with their mineralogy and microstructure. Additionally, the study assesses the impact of diagenesis on quality of the unconventional tight carbonate resources. Experimental techniques include Scanning Electronic Microscopy (SEM), Energy-Dispersive X-ray Spectroscopy (EDS), and X-ray diffraction (XRD), photomicrography, Helium porosity and steady state gas permeability. Results revealed that the porosity was in range of 2.12 to 8.5% with an average value of 4.5% and the permeability was ranging from 0.013 to 5.8mD. Thin section study, SEM-EDS, and XRD analyses revealed that the samples mostly contain carbon (C), calcium (Ca), and magnesium (Mg) as dominant elemental components.The main carbonate components observed were calcite, dolomite, micrite, Ferron mud, bioclasts and intermixes of clay minerals and cementing materials. The analysis shows that: 1) the permeability and porosity cross plot, the permeability and slippage factor values cross plots appears to be scattered, which showed weaker correlation that was the reflection of carbonate rock heterogeneity. 2) The permeability and clay mineralogy cross plots have resulted in poor correlation in these carbonate samples. 3) Several diagenetic processes had influenced the quality of carbonates of Jakkher Group, such as pore dissolution, calcification, cementation, and compaction. 4) Reservoir quality was mainly affected by inter-mixing of clay, cementation, presence of micrite muds, grain compactions, and overburden stresses that all lead these carbonate reservoirs to ultra-tight reservoirs and are considered to be of very poor quality. 5) SEM and thin section observations shows incidence of micro-fractures and pore dissolution tended to improve reservoir quality.


2018 ◽  
Vol 73 ◽  
pp. 02021
Author(s):  
Fahrudin ◽  
Eka Sainyakit ◽  
Ahmad Syauqi Hidayatillah ◽  
Purnaning Tuwuh Triwigati ◽  
Muhajir

The North East Java Basin is known to be one of the basins that consist of Miocene carbonate rocks, like the reef carbonate of Tuban Formation. It has the potential hydrocarbons that can be explored. Therefore, the FMI log analysis is very important to identify carbonate rocks of Tuban Formation to know facies and characteristics of that carbonate rocks. The method used descriptive and analysis process of FMI and Gamma Ray log to determine facies of the carbonate rock and the system tract. Based on the result of FMI log analysis, there are variations lithofasies include mudstone, wackestone, packstone, grainstone, floatstone, rudstone and claystone. A collection of rock associations can interpret the reef facies. It involves back reef facies, reef core facies, and fore reef facies. The changes of lithofasies and reef facies are caused by sea level fluctuations and subsidence resulting in the system tract. The system tracts generated in the research area include transgressive and highstand system tract.


2012 ◽  
Author(s):  
Mohd Zaidi Jaafar ◽  
Ali Pourbasirat

Telaga pintar merujuk kepada telaga yang mengandungi downhole sensors dan injap kawalan aliran masuk (ICV) yang dipasang pada tiub pengeluaran. Telaga ini membenarkan pengendali untuk merekodkan kadar aliran bendalir, suhu dan tekanan yang berterusan semasa pengeluaran. Baru–baru ini, pengukuran streaming potential dalam telaga pintar telah dicadangkan untuk memantau pencerobohan air. Walau bagaimanapun, masih terdapat ketidakpastian yang signifikan yang dikaitkan dengan tafsiran ukuran, terutamanya mengenai pekali gandingan streaming potential. Ini adalah ciri petrofizik utama yang menentukan magnitud streaming potential untuk potensi bendalir yang tertentu. Magnitud streaming potential pada asasnya berkait dengan kadar aliran bendalir, sifat–sifat bendalir (khususnya kemasinan), dan sifat–sifat matriks batuan. Pekali gandingan telah diukur secara uji kaji dalam teras batu pasir yang tepu dengan kemasinan air garam yang berbeza, tetapi sangat sedikit hasil ujikaji telah diterbitkan bagi batuan karbonat. Bilangan reservor karbonat yang besar di seluruh dunia menyarankan bahawa pengukuran streaming potential dalam batuan karbonat juga penting. Dalam kajian ini, kami kemukakan nilai pekali gandingan streaming potential bagi batu karbonat yang tepu dengan berbagai kemasinan air garam. Seperti yang kami jangkakan, streaming potential bagi teras itu adalah kecil tetapi masih boleh diukur, dan kemasinan yang lebih tinggi memberikan pekali gandingan streaming potential yang lebih kecil. Keputusan yang diperolehi adalah konsisten hasil penggunaan elektrod yang direka khas dan ujikaji pam berpasangan untuk menghapuskan potensi elektrik palsu. Kami mendapati bahawa pekali gandingan streaming potential di dalam batu karbonat adalah lebih rendah berbanding dengan yang ada di teras batu pasir yang ditepukan dengan kemasinan air garam yang sama. Pemerhatian ini boleh dijelaskan dengan membandingkan perbezaan titik caj sifar (pzc) di antara kedua–dua jenis batu. Secara kualitatif, hasil ujikaji menunjukkan bahawa pengukuran streaming potential boleh digunakan untuk memantau pencerobohan air di dalam reservor karbonat, sama seperti ia digunakan untuk reservor batu pasir. Kata kunci: Streaming potential; elektrokinetik; pemantauan bawah telaga; telaga pintar; water encroachment; kawalan pengeluaran air; batu karbonat Smart wells refer to wells containing downhole sensors and inflow control valves (ICV) mounted on the production tubing. These wells allow the operator to record fluid flow rates, temperature and pressure incessantly. Recently, streaming potential measurement in smart wells has been proposed to monitor water encroachment. However, there are still significant uncertainties associated with the interpretation of the measurements, particularly concerning the streaming potential coupling coefficient. This is a key petrophysical property that dictates the magnitude of the streaming potential for a given fluid potential. Streaming potential magnitude is basically related to the fluid flow rate, fluid properties (particularly salinity), and the rock matrix properties. The coupling coefficient has been measured experimentally in sandstone cores saturated with different brine salinities, but very little works have been published on carbonate rocks. The huge number of carbonate reservoirs around the world suggests that measurement of streaming potential in carbonate rocks is also important. In this study, we present value of streaming potential coupling coefficient in a carbonate rock saturated with various salinities of brine. As we expected, streaming potential in such core is small but measurable and higher salinity gives smaller streaming potential coupling coefficient. Consistent results are obtained using specially designed electrodes and paired pumping experiments to eliminate spurious electrical potentials. We noticed that streaming potential coupling coefficient in carbonate rock is lower compared to the one in sandstone cores saturated with the same salinity of brine. This observation could be explained by comparing the difference in Point of zero charges (pzc) between those two types of rock. Qualitatively, the result suggests that measurements of streaming potential could be applied for monitoring water encroachment in carbonate reservoirs, in the same manner it is applied for sandstones reservoirs. Key words: Streaming potential; electrokinetics; downhole monitoring; intelligent wells; water encroachment; produced water control; carbonate rocks


Author(s):  
Si Y. Lee

Primary objective of the work is to model resin particles within the column during the particle fluidization and sedimentation processes and to understand hydraulic behavior for particles within column during the resin fluidization and sedimentation processes. The modeling results will assist in interpreting experimental results, providing guidance on specific details of testing design, and establishing a basic understanding of resin particle’s hydraulic behavior within the column. The model was benchmarked against the literature data and the test data conducted by Savannah River National Laboratory at Savannah River Site (SRS). A scoping analysis effort has been undertaken to address the feasibility of simulating the basic fluidization and sedimentation aspects pertinent to the resin addition/removal process considered here. The existing computational fluid dynamics (CFD) code Fluent was chosen for this effort. Both fluidization and sedimentation of granular particles (i.e., of varying sizes) were based on an Eulerian model for granular flow. A two-dimensional axial symmetrical cylindrical geometry was chosen to perform the solid-fluid simulations. The column consisted of a fluid region of 48” in diameter by 94” in height where at both the top and bottom boundaries liquid fluid could pass through, but resin particle could not (i.e., assuming screens at both ends).


2021 ◽  
Author(s):  
Latifa Obaid Alnuaimi ◽  
Mehran Sohrabi ◽  
Shokoufeh Aghabozorgi ◽  
Ahmed Alshmakhy

Abstract Simulation of Water-Alternating-Gas (WAG) Experiments require precise estimation of hysteresis phenomenon in three-phase relative permeability. Most of the research available in the literature are focused on experiments performed on sandstone rocks and the study of carbonate rocks has attracted less attention. In this paper, a recently published hysteresis model by Heriot-Watt University (HWU) was used for simulation of WAG experiments conducted on mixed-wet homogenous carbonate rock. In this study, we simulated immiscible WAG experiments, which were performed under reservoir conditions on mixed-wet carbonate reservoir rock extracted from Abu Dhabi field by using real reservoir fluids. Experiments are performed with different injection scenarios and at high IFT conditions. Then, the results of the coreflood experiments were history matched using 3RPSim to generate two-phase and three-phase relative permeability data. Finally, the hysteresis model suggested by Heriot-Watt University was used for the estimation of hysteresis in relative permeability data. The performance of the model was compared with the experimental data from sandstones to evaluate the impact of heterogeneity on hysteresis phenomenon. It was shown that the available correlations for estimation of three-phase oil relative permeability fail to simulate the oil production during WAG experiments, while the modified Stone model suggested by HWU provided a better prediction. Overall, HWU hysteresis model improved the match for trapped gas saturation and pressure drop. The results show that the hysteresis effect is less dominant in the carbonate rock compared to the sandstone rock. The tracer test results show that the carbonate rock is more homogenous compared to sandstone rock. Therefore, the conclusion is that the hysteresis effect is negligible in homogenous systems.


2015 ◽  
Vol 123 ◽  
pp. 256-266 ◽  
Author(s):  
Gilberto Peixoto da Silva ◽  
Daniel R. Franco ◽  
Giovanni C. Stael ◽  
Maira da Costa de Oliveira Lima ◽  
Ricardo Sant'Anna Martins ◽  
...  

SPE Journal ◽  
2012 ◽  
Vol 18 (02) ◽  
pp. 243-263 ◽  
Author(s):  
Maryam Mousavi ◽  
Maša Prodanovic ◽  
David Jacobi

Summary Carbonate rocks are complex in structure and pore geometry and display heterogeneity on all length scales. In this paper, carbonate rocks are described on the basis of their contents and pore geometry for use in pore-scale modeling. Definitions of grains and porosities are based on other carbonate-rock classifications; we did not invent new concepts. On the basis of carbonate content (grain, mud, and cement), carbonate rocks were divided into three types: muddy, grainy, and mixed. Each type was divided into subtypes on the basis of pore geometries defined by other researchers. Pore-size distribution of Lønøy (2006) was used for each subtype. We review existing carbonate-rock models and suggest approaches, and show preliminary flow-simulation results, for pore-scale modeling of different grains, cement, and pore geometry in these complex rocks.


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